Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B11/00—Pressing molten glass or performed glass reheated to equivalent low viscosity without blowing
  • C03B11/06—Construction of plunger or mould
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B11/00—Pressing molten glass or performed glass reheated to equivalent low viscosity without blowing
  • C03B11/12—Cooling, heating, or insulating the plunger, the mould, or the glass-pressing machine; cooling or heating of the glass in the mould
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B11/00—Pressing molten glass or performed glass reheated to equivalent low viscosity without blowing
  • C03B11/06—Construction of plunger or mould
  • C03B11/08—Construction of plunger or mould for making solid articles, e.g. lenses
  • C03B11/082—Construction of plunger or mould for making solid articles, e.g. lenses having profiled, patterned or microstructured surfaces
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B11/00—Pressing molten glass or performed glass reheated to equivalent low viscosity without blowing
  • C03B11/06—Construction of plunger or mould
  • C03B11/08—Construction of plunger or mould for making solid articles, e.g. lenses
  • C03B11/088—Flat discs
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2215/00—Press-moulding glass
  • C03B2215/40—Product characteristics
  • C03B2215/41—Profiled surfaces
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2215/00—Press-moulding glass
  • C03B2215/40—Product characteristics
  • C03B2215/44—Flat, parallel-faced disc or plate products
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2215/00—Press-moulding glass
  • C03B2215/40—Product characteristics
  • C03B2215/46—Lenses, e.g. bi-convex
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2215/00—Press-moulding glass
  • C03B2215/65—Means for releasing gas trapped between glass and press die

Definitions

• the present invention relates to a method for mass-producing a glass substrate for a magnetic disk most suitable for a recording medium such as a magnetic disk at a low cost.
• a glass substrate for a magnetic disk has been manufactured by a polishing method in which a glass substrate for a magnetic disk is cut out to a predetermined size and then polished to obtain a smooth surface.
• a polishing method in which a glass substrate for a magnetic disk is cut out to a predetermined size and then polished to obtain a smooth surface.
• ultra-smoothness has been required for the substrate surface, and high precision has been required for the polishing process, which is extremely difficult technically. Therefore, polishing such substrates one by one has a drawback that the number of steps is large and the cost is high.
• the press molding method that transfers the molding surface of the mold by heating, molding, and cooling the glass material does not require post-processing, so it is inexpensive, has high productivity, and has high quality. Numerous studies have already been made in the field of device manufacturing, and practical use is being pursued.
• the substrate thickness is small, the outside diameter is large, Forming a material with a large ratio of plate thickness to outer diameter is a different challenge than molding a material with a relatively small ratio of lens thickness to outer diameter, such as an optical element, that has a curvature. Had.
• Japanese Patent Application Laid-Open No. 11-1763237 discloses a body mold, a lens surface molding mold slidably fitted to the body mold, and a body mold holder for holding the periphery of the body mold.
• a molding method using a lens molding apparatus wherein the heat shrinkage of the body mold is smaller than the heat shrinkage of the lens material, and the heat shrinkage of the body mold holder is larger than the heat shrinkage of the lens material. It is shown.
• this device it is possible to obtain a molded glass lens having a desired thickness by defining the thickness dimension of the barrel holder, and the heat shrinkage of the barrel holder is smaller than the heat shrinkage of the lens material. Since the lens is configured to be large, the upper pressing force always acts on the lens during the cooling process, so that the lens can obtain the desired surface shape.
• Japanese Patent Application Laid-Open No. 2-26843 discloses a method of using a thin glass material to be molded in order to form a glass molded body having a large outer diameter and a small thickness.
• the glass material to be molded since the glass material to be molded has a shape close to the glass molded body, it can be easily heated, has a small amount of deformation, and can easily shorten the molding cycle.
• the present invention solves the above-mentioned drawbacks of the prior art, has a glass substrate for a magnetic disk having an ultra-smooth surface, and can be manufactured by press molding, a glass substrate molding die and a glass substrate capable of obtaining the same
• An object of the present invention is to provide a glass material for molding and a method for producing a glass substrate.
• the present invention has the following configuration.
• the glass substrate molding die of the present invention includes a pair of upper and lower dies and a regulating member that regulates a gap between the upper and lower dies, and is a glass substrate molding die for producing a parallel plate-shaped glass substrate.
• the amount of heat shrinkage of the regulating member is smaller than the amount of heat shrinkage of the glass substrate material. Since the amount of heat shrinkage of the regulating member that regulates the gap in the thickness direction of the upper and lower molds is smaller than the amount of heat shrinkage of the glass substrate material, the upper and Z or lower surfaces of the glass substrate are molded during molding and cooling. And separate. Therefore, a glass substrate having a diameter larger than the thickness and an ultra-smooth surface can be easily manufactured.
• the material of the regulating member having a smaller heat shrinkage than the glass substrate material varies depending on the glass material used, and examples thereof include tungsten carbide, alumina, chromium, sapphires, and zircon.
• the molding die of the present invention exerts the above effects particularly remarkably when used for molding a glass substrate in which the relationship between the outer diameter X and the thickness Y satisfies X> 40Y.
• the regulating member in the molding die of the present invention has a gap of 1 mm between the upper and lower molds. It is preferable to regulate as follows.
• a concave portion in at least one of the central portions of the upper and lower molds. Furthermore, the number of types that can be identified can be increased by providing a plurality of the concave portions.
• the glass substrate forming glass material of the present invention is used to manufacture a parallel plate-shaped glass substrate using a forming die including a pair of upper and lower molds and a regulating member for regulating a gap between the upper and lower molds.
• a glass material used for the molding member having a heat shrinkage larger than the heat shrinkage of the regulating member, and, when placed on the molding die, makes point contact with the molding die;
• the present invention is characterized in that when the number of contact portions with the molding die increases due to the pressure forming, the contact portions are continuously deformed so that air is not entrained in the contact portions.
• the glass material is placed in a molding die comprising a pair of upper and lower molds and a regulating member for regulating the gap between the upper and lower molds, the glass material is pressure molded.
• the heat shrinkage of the regulating member is smaller than the heat shrinkage of the glass material, and the glass material is in point contact with the molding die when placed in the molding die.
• the heat shrinkage of the regulating member that regulates the gap in the thickness direction of the upper and lower molds is smaller than the heat shrinkage of the glass material. Then, after molding and cooling, the upper and lower surfaces of the glass substrate are separated from the mold. Therefore, a glass substrate having a diameter larger than the thickness and an ultra-smooth surface can be easily manufactured. Furthermore, since the glass material is initially formed in point contact with the mold and then formed while increasing the contact area so that air is not entrained, the molding yield is good and a high quality glass substrate is formed. Can be obtained stably. As a shape of the glass material for realizing this, for example, it is preferable that the vertical cross section is circular or elliptical.
• the second method of manufacturing a glass substrate of the present invention includes a first step of placing a glass material in a molding die including a pair of upper and lower molds and a regulating member for regulating a gap between the upper and lower molds. A second step of heating and softening the glass material, a third step of press-molding the glass material on a parallel plate-shaped glass substrate, a fourth step of cooling the glass substrate, A fifth step of removing the glass substrate, wherein the heat shrinkage of the regulating member is smaller than the heat shrinkage of the glass material.
• the third method of manufacturing a glass substrate of the present invention includes: a first step of placing a glass material on a tray; a second step of heating and softening the glass material; and A third step of placing the glass material in a molding die comprising a pair of upper and lower molds and a regulating member for regulating the gap between the upper and lower molds; and pressure molding the glass material into a parallel plate-like glass substrate.
• a fourth step of cooling the glass substrate, a fifth step of cooling the glass substrate, and a sixth step of removing the glass substrate It is characterized by being smaller than the amount.
• the pressurization is continued until the temperature of the glass substrate reaches at least the glass transition temperature in the cooling step. Thereby, the shape accuracy of the mold can be accurately transferred to the glass substrate.
• the relationship between the outer diameter X and the thickness Y of the glass substrate satisfies X> 40Y.
• the regulating members It is preferable to regulate the gap between the upper and lower molds to 1 mm or less. Further, it is preferable to provide a concave portion in at least one of the central portions of the upper and lower molds, and it is more preferable that the concave portion is plural.
• the glass substrates obtained by the first, second, and third manufacturing methods are suitable for a magnetic disk.
• the glass substrate does not affect the surface of the glass substrate. It is also possible to include special bubbles in the glass substrate.
• a glass substrate having a desired ultra-smooth surface and having no undulation can be obtained by die molding without the need for post-processing. Therefore, it is possible to obtain an inexpensive and stable quality glass substrate for a magnetic disk.
• FIG. 1 (A) is a cross-sectional view of a glass substrate molding die according to Embodiments 1 and 2 of the present invention
• FIG. 1 (B) is a glass substrate molding die according to Embodiments 3 and 4 of the present invention. It is sectional drawing.
• FIG. 2 is a top view of a glass substrate molding die according to Embodiments 1 to 4 of the present invention.
• FIG. 3 is an external view of a glass material for forming a glass substrate of the present invention.
• FIG. 4 is a cross-sectional view showing an outline of a glass substrate forming apparatus according to Embodiments 1 and 2 of the present invention.
• FIG. 5 is a cross-sectional view schematically illustrating a glass substrate forming apparatus according to Embodiments 3 and 4 of the present invention.
• FIG. 6 is an external view of the glass substrate of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION
• FIGS. (Embodiment 1)
• FIG. 1 (A) is a cross-sectional view showing a state in which a glass substrate forming glass material 4 is placed in a glass substrate forming die according to Embodiment 1 of the present invention.
• the glass substrate molding die is provided with an upper die 1 having a molding surface 1a for obtaining a glass substrate 19 (FIG. 6) having a desired surface roughness, and is arranged substantially coaxially with and opposed to the upper die 1. Between a lower mold 2 having a molding surface 2 a for obtaining a glass substrate 19 having a desired surface roughness, and a molding surface 1 a of the upper mold 1 and a molding surface 2 a of the lower mold 2 when molding is completed. And a regulating member 3 that regulates the gap of the airbag.
• the surface roughness (R a) of the molding surfaces 1 a and 2 a at this time is suitably 5 nm or less for a magnetic disk, preferably 2 nm or less, and more preferably 1 nm or less.
• the gap varies depending on the thickness of the glass substrate to be formed, but is substantially the same as the thickness of the glass substrate, and is at most about 1 mm.
• FIG. 2 is a view of the upper die 1 provided with the concave portion 5 as viewed from above.
• convex portions to which the concave portions 5 are transferred are formed on both surfaces of the glass substrate.
• eight small recesses arranged in a row in the center of the mold, and locations corresponding to the eight recesses (below each) are 0 to 8 depending on the mold number.
• the recesses are arranged in a row in various combinations.
• WC tungsten carbide
• IGE Yu Roy trademark of Sumitomo Electric Industries, Ltd.
• FIG. 3 shows an example of the shape of the glass material 4 for forming a glass substrate.
• the shape of the glass material may be any shape as long as it makes point contact in the initial state of being placed on the mold, and in the deformation process, the contact part continuously expands so that air does not get caught in the mold.
• the vertical cross section is preferably circular or elliptical.
• FIG. 4 shows the glass substrate molding die shown in Fig. 1 (A) and the glass substrate molding material shown in Fig. 3 (B) (outer diameter 20 mm, thickness 7 mm, cross-section in the thickness direction is approximately elliptical.
• FIG. 7 is a cross-sectional view showing an outline of a glass substrate forming apparatus for forming the glass substrate 19 shown in FIG.
• the upper die 1 is fixed to the heat sink 6, and the heat sink 6 is fixed to the chamber 11 through an insulating plate 8.
• the lower mold 2 is fixed to a heater 7, and the heater 7 is fixed on a cylinder rod 10 driven up and down by a cylinder 11 via an insulating plate 9.
• the ring-shaped regulating member 3 is placed on the flange surface of the lower die 2 so that the gap between the upper die 1 and the lower die 2 becomes 0.635 mm when the molding is completed.
• the glass substrate to be made is a magnetic disk glass substrate with an outer diameter of 65 mm and a thickness of 0.635 mm.
• the glass material 4 supplied to the mounting table 15 is substantially centered on the lower mold forming surface 2a in the chamber 1 2 in the N 2 atmosphere by the glass material chuck 16 from the outside of the chamber 1 2. Is placed.
• lower die 2 rises slowly by cylinder 11.
• the heaters 6 and 7 are turned on.
• the glass material 4 is heated at 770 (the temperature at which the glass viscosity becomes 7.1 poise), and the inside of the material is heated to this temperature.
• the glass material 4 expands with the heating, and is deformed by fixing the upper and lower molds. At this time, since a bubble may be involved, the lower mold 2 is held with a low load.
• the glass material 4 is formed by the regulating member 3 to have a thickness of 0.635 mm, which is the same as the space created between the upper mold 1 and the lower mold 2.
• the power to the heaters 6 and 7 is turned off, and the upper mold 1, the lower mold 2, the regulating member 3, and the glass material 4 are cooled while the high load is maintained.
• the cooling may be performed forcibly, but the cooling must be performed so that the temperature in the surface of the molding die is as uniform as possible.
• the upper mold 1, the lower mold 2, the regulating member 3, and the glass material 4 contract. Since the gap between the upper mold 1 and the lower mold 2 is regulated by the regulating member 3, the amount of the gap depends on the amount of contraction of the regulating member 3. Since the heat shrinkage of the glass material 4 is larger than the heat shrinkage of the regulating member 3, As the temperature decreases, the glass material 4 can be released from the upper and lower molds gradually.
• a high load is applied to the glass substrate molding die by the cylinder 11 until the temperature of the glass material 4 reaches the glass transition point temperature of 539 ° C., and thereafter the pressure is reduced to a low load.
• the lower mold 2 is lowered by the cylinder 11 and returns to the home position.
• the glass substrate 19 remaining in the molding die was transferred between the cooling room 17 and the cooling room 18 in the cooling step by a transfer pad (not shown), and was gradually cooled. Later, it is removed from the molding device and molding is completed.
• FIG. 6C shows an external view of the glass substrate 19 according to the present embodiment.
• the resulting glass substrate 19 has a super-smooth surface with a surface roughness of 1 nm, the surface of the mold is almost transferred, and has no flatness within 5 m. It has a projection 22 for determining the model number.
• Embodiment 2 of the present invention is the same as Embodiment 1 except that a glass material for forming a glass substrate 4 uses a material containing bubbles inside.
• the glass substrate 19 according to the present invention has a structure containing bubbles 21 inside as shown in FIG. 6 (B). That is, the specific gravity is lighter than that of the glass substrate 19 shown in FIG. 6A or FIG. 6C which does not include the bubble 21 and is effective as a glass substrate for a magnetic disk required to rotate at a high speed.
• FIG. 1 (B) is a cross-sectional view showing a state in which a glass substrate molding glass material 4 is placed in a glass substrate molding die according to Embodiment 3 of the present invention.
• An upper mold 1 provided with a molding surface 1a for obtaining a glass substrate 1 9 having a surface roughness of 1 (FIG. 6), and a glass substrate 1 having a desired surface roughness disposed so as to be substantially coaxially opposed to the upper mold 1
• a lower die 2 having a molding surface 2a for obtaining a molding member 9; and a regulating member 3 for regulating a gap between the molding surface 1a of the upper die 1 and the molding surface 2a of the lower die 2 when molding is completed.
• It is composed of
• the surface roughness (R a) of the molding surfaces 1 a and 2 a at this time is suitably 5 nm or less for a magnetic disk, preferably 2 nm or less, and more preferably 1 nm or less.
• the gap varies depending on the thickness of the glass substrate to be formed, but is substantially the same as the thickness of the glass substrate, and is at most about 1 mm.
• FIG. 2 is a view of the upper mold 1 provided with the concave portion as viewed from above.
• each member of the mold for forming glass substrates is made of a cemented carbide mainly composed of tungsten carbide (WC) (“IGE Yu Roy” (trademark of Sumitomo Electric Industries, Ltd.)
• the molding surfaces 1a and 2a are added to a desired surface roughness, and are covered with a platinum (Pt) -based alloy protective film.
• FIG. 5 shows the results shown in Fig. 6 (C) using the glass substrate molding die shown in Fig. 1 (B) and the glass substrate molding material (22.1 mm diameter sphere) shown in Fig. 3 (A).
• FIG. 2 is a cross-sectional view showing an outline of a glass substrate forming apparatus for forming a glass substrate 19;
• the glass tray 20 used in the step of placing the glass material 4 and heating and softening is made of a material having good releasability from the glass material 4 at a high temperature, for example, carbides such as SiC and TiC, carbon, and A. It is made of a nitride such as 1N or TiN, or is formed on the surface by various film forming techniques such as a CVD method, and is finished to a desired surface roughness.
• Fig. 3 (A) also has a point contact in the initial state of being placed on the mold, and the contact part continuously expands so that air does not get caught in the mold during the deformation process. is there.
• the upper mold 1 is fixed to the heater 6, and the heater 6 is fixed to the chamber 11 via a heat insulating plate 8.
• the lower mold 2 is fixed to a heater 7, and the heat sink 7 is fixed on a cylinder rod 10 driven up and down by a cylinder 11 via an insulating plate 9.
• the ring-shaped regulating member 3 is placed on the molding surface 2a of the lower die 2 so that the gap between the upper die 1 and the lower die 2 becomes 0.8 mm when the molding is completed.
• the glass substrate to be made is a glass substrate for magnetic disks with an outer diameter of 95 mm and a thickness of 0.8 mm.
• the glass material 4 supplied to the glass material tray 20 on the mounting table 15 is transferred between the preheated upper heater 13 and the preheated heater 14 in the N 2 atmosphere by the glass material check 16. You.
• the glass material 4 is heated at 750 (the temperature at which the glass viscosity becomes 6.4 poise), and the inside of the material is heated until this temperature is reached (heating softening step).
• the glass material 4 is transported by the glass material chuck 16 again between the upper mold 1 and the lower mold 2 in the chamber 1 12 while being placed on the glass material tray 20. Then, only the glass material 4 is checked by a transfer device (not shown), and after the glass material chuck 16 and the glass material tray 20 are retracted, the glass material chuck 16 and the glass material tray 20 are placed almost at the center on the molding surface 2 a of the lower mold 2. .
• the glass material 4 is formed by the regulating member 3 to have the same thickness of 0.8 mm as the gap created between the upper mold 1 and the lower mold 2.
• the upper mold 1 and the lower mold 2 are set to 600 by heaters 6 and 7, respectively. Since the glass material 4 after the deformation has a thin thickness of 0.8 mm, it is immediately cooled to this temperature.
• the power of heaters 6 and 7 is turned off, and the upper mold 1, lower mold 2, regulating member 3 and glass material 4 are cooled while the high load is maintained.
• the cooling may be performed forcibly, but the cooling must be performed so that the temperature in the surface of the molding die is as uniform as possible.
• the upper mold 1, the lower mold 2, the regulating member 3, and the glass material 4 contract.
• the upper die 1 and lower die 2 are voided by the regulating member 3. Therefore, the gap amount depends on the contraction amount of the regulating member 3. Since the heat shrinkage of the glass material 4 is greater than the heat shrinkage of the regulating member 3, the glass material 4 can be gradually released from the upper and lower molds as the temperature decreases.
• a high load is applied to the glass substrate forming die by the cylinder 11 until the temperature of the glass material 4 reaches the glass transition point temperature of 492, and then the pressure is reduced to a low load.
• the lower mold 2 is lowered by the cylinder 11 and returns to the home position.
• the glass substrate 19 remaining in the molding die is transferred between the upper cooling fan 17 and the lower cooling fan 18 in the cooling process by a transfer pad (not shown), and after being gradually cooled. , Removed from the molding equipment, and the molding is completed.
• FIG. 6C shows an external view of the glass substrate 19 according to the present embodiment.
• the obtained glass substrate 19 has almost the same shape of the mold forming surface, has an ultra-smooth surface with a surface roughness of 0.6 nm, has a flatness of 5 zm or less, and has no undulation. It has a protrusion 22 for determining the mold number.
• the heating temperature of the glass material 4 by the preheating upper heater 13 and the preheating lower heater 14 is set to 700 ° C. (the temperature at which the glass viscosity becomes 7.1 poise).
• the outer diameter is 95 mm and the thickness is the same as in the third embodiment.
• the external shape of the obtained glass substrate 19 is as shown in FIG. 6 (C), and the glass substrate 19 has an ultra-smooth surface with a surface roughness of 0.6 nm, on which the shape of the mold forming surface is almost transferred. It has a flatness of 5 or less, no undulation, and has a convex portion 22 at the center for identifying the number of the molding die.

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• 1999
  • 1999-04-27 US US09/719,695 patent/US6539750B1/en not_active Expired - Lifetime
• 2000
  • 2000-04-27 KR KR10-2000-7015082A patent/KR100390637B1/ko not_active IP Right Cessation
  • 2000-04-27 JP JP2000615342A patent/JP3565784B2/ja not_active Expired - Fee Related
  • 2000-04-27 TW TW089107970A patent/TW466216B/zh not_active IP Right Cessation
  • 2000-04-27 WO PCT/JP2000/002811 patent/WO2000066504A1/ja active IP Right Grant
• 2003
  • 2003-02-04 US US10/358,468 patent/US6718799B2/en not_active Expired - Fee Related

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